The present invention relates to a process for manufacturing primary structural elements with curing in a female tool to assist required dimensional tolerances of such components and the absence of porosity in the area of radii while preventing outward flow of resin. The manufactured structural components may have both transverse and longitudinal overthicknesses and reinforcements.
More specifically, the present invention intends to develop the necessary theoretical concepts and the related manufacturing processes, to carry out laminating, forming and curing of primary structures, such as front and rear aircraft spars, in a female tool with determined dimensional limitations.
The technology corresponding to curing in a female tool by caul plates is novel and has been totally developed by the applicant.
One of the most productive industrial applications of the invention is to manufacture large parts whose dimensional quality is assured.
The technology of curing in a female tool by support on respective caul plates, totally developed by the present invention, is entirely new and for the first time allows an aircraft spar or other primary structure to be manufactured by a process to be described more fully later, including automatic taping, thermoforming and curing in a female tool. The invention is the result of the research carried out regarding flying-surfaces or so called LFS (Large Flying-Surfaces) and in FB 4.1 preliminary certification tests (torsion box with fuel pressure).
From the results of the previous experiments as well as from related manufacturability studies and tests, it is found that the application of the process of the invention is feasible and reliable for its use in manufacturing high resistant structures with strict quality requirements.
This invention is applicable to the manufacture of formed composite material parts.
These parts may include:
Aircraft structures and controls such as flying-surface coatings, spars, ribs, fixtures
Space vehicles.
Marine and land vehicles.
Industrial Machinery and equipment.
The manufacturing processes involved to obtain these parts are:
Laminating composite material (manual or automatic).
Cutting composite material.
Hot forming composite material.
Handling and positioning stiffeners, parts and tools.
Autoclave curing.
The materials used in the manufacture of these parts may be integrated by different resins and different fiber types, such as:
Fiberglass.
Carbon fiber.
KEVLAR fiber (aramid fiber)
Boron fiber.
Epoxy resin.
Thermoplastic resin.
Other heat-stable resins.
The object of the invention is a process for manufacturing structural parts of composite material in which the curing of the parts occurs inside a female tool. This is obtained by means of suitable tooling permitting control and prevention of resin flow during cycle.
The cured part may be a wing spar, a stabilizer, both horizontal and vertical, or any carbon fiber component with a U-shaped transverse section.
The essence of the process of the present invention is to design a female tool permitting a complete compaction of the radii without significant porosity and with a high dimensional accuracy. For this purpose, relevant caul plates are used to attain the aforementioned object.
The purpose of the invention is applicable to the parts obtained by any lamination process (manual, automatic) but the novelty introduced by the invention is that it permits the manufacture of spars with automatic taping and hot forming, which avoids an expensive manual process for fitting fabrics, especially if in a tape form.